Spinous process fixation system and mehtods thereof

ABSTRACT

An implantable device may include a barrel, the barrel having an upper portion and a lower portion. The implantable device may further include an actuator assembly disposed in the barrel, and a central screw that extends from a rear ramped actuator through a front ramped actuator. The implantable device may further include a first plate having multiple projections extending from one side of the first plate. The implantable device may further include a second plate having multiple projections extending from one side of the second plate, the second plate configured to be received on the central screw. The barrel may be configured to transition from a collapsed form having a first height to an expanded form having a second height and wherein the second height is greater than the first height.

CROSS-REFERENCE TO RELATED APPLICATIONS

This patent application is a continuation of U.S. patent applicationSer. No. 17/497,453 filed on Oct. 8, 2021, which is a continuation ofU.S. patent application Ser. No. 16/281,133 filed on Feb. 21, 2019(published as U.S. Pat. Pub. No. 2019-0254721), which is a continuationof U.S. patent application Ser. No. 14/923,894 filed on Oct. 27, 2015,now U.S. Pat. No. 10,251,680, which is a continuation of U.S. patentapplication Ser. No. 13/799,364 filed on Mar. 13, 2013, now U.S. Pat.No. 9,198,697, the entire disclosures of all of which are incorporatedherein by reference for all purposes.

FIELD OF THE INVENTION

This description relates to medical devices and systems and moreparticularly to a spinous process fixation system and methods thereof.In particular, in one or more implementations, this description relatesto spinous process fusion devices that distract and/or immobilize thespinous processes of adjacent vertebrae.

BACKGROUND

A variety of medical devices and medical device systems may be implantedwithin a body of a patient to provide support to a portion or portionsof the patient's body. For example, some medical devices may beimplanted and coupled to backbones or portions of a spine of a patientand may be configured to provide support to the spinal bone structure ofthe patient.

Typically, weaknesses in the spine are corrected using devices that fuseone or more vertebrae together. It may be desirable to have animplantable device that provides for structural stability to adjacentvertebrae and to achieve supplemental fusion to treat weaknesses in thespine due to degenerative disc disease, spondylolisthesis, trauma (i.e.,fracture or dislocation), tumor and/or other causes.

SUMMARY

According to one general aspect, an implantable device includes abarrel. The barrel has a first portion and a second portion. Theimplantable device includes a first plate having multiple projectionsextending from one side of the first plate, where the first plate isconfigured to movably couple to the first portion of the barrel. Theimplantable device includes a second plate having multiple projectionsextending from one side of the second plate, where the second plate isconfigured to movably couple to the second portion of the barrel. Thebarrel is configured to transition from a collapsed form having a firstheight to an expanded form having a second height, where the secondheight is greater than the first height.

Implementations may include one or more of the following features. Forexample, the barrel may include a frame, a first endplate having acurved shape and a second endplate having a curved shape. The firstendplate and the second endplate may be coupled to the frame to form thebarrel, where the barrel has a bulleted shape in both a lateraldirection and a posterior direction. The barrel may include a frame, afirst endplate, a second endplate, a first actuator having a split rampinserted into the frame, a second actuator having a split ramp insertedinto the frame and a central screw inserted through the first actuatorand the second actuator, where the first actuator and the secondactuator are configured to act on the first endplate and the secondendplate in response to a rotation of the central screw. The barrel mayinclude a first window and a second window, where the first window andthe second window may be configured to receive graft packing material.The barrel may include a first endplate having a shaped groove and asecond endplate having a shaped groove.

For example, in one implementation, the first portion and the secondportion may be rails that extend from a same side of the barrel. Forexample, in another implementation, the first portion and the secondportion may be rails that each extend from a different side of thebarrel.

For example, the first plate and the second plate are each shaped in alordotic profile. The first plate may include a bushing to enable thefirst plate to angulate about the bushing and the second plate mayinclude a bushing to enable the second plate to angulate about thebushing. The first plate may be locked in position using a first setscrew at any position within a range of motion for the first plate andthe second plate may be locked in position using a second set screw atany position within a range of motion for the second plate. The firstset screw may include a cup-shaped end to lock the first plate inposition and the second set screw may include a cup-shaped end to lockthe second plate in position.

In another general aspect, an implantable device includes a barrelhaving a first portion and a second portion, a first plate havingmultiple projections extending from one side of the first plate, wherethe first plate is configured to movably couple to the first portion ofthe barrel and to angulate about an axis of the first portion, and asecond plate having multiple projections extending from one side of thesecond plate, where the second plate is configured to movably couple tothe second portion of the barrel and to angulate about an axis of thesecond portion. The first plate and the second plate are each shaped ina lordotic profile.

Implementations may include one or more of the following features. Forexample, the first plate may be configured to angulate up to about 25degrees about the axis of the first portion and the second plate may beconfigured to angulate up to about 25 degrees about the axis of thesecond portion. In one implementation, the first portion and the secondportion may be rails that extend from a same side of the barrel. Inanother implementation, the first portion and the second portion may berails that each extend from a different side of the barrel.

For example, the barrel may be configured to transition from a collapsedform having a first height to an expanded form having a second height,where the second height is greater than the first height. The firstplate may be locked in position using a first set screw at any positionwithin a range of motion for the first plate, where the first set screwhas a cup-shaped end, and the second plate may be locked in positionusing a second set screw at any position within a range of motion forthe second plate, where the second set screw has a cup-shaped end.

In another general aspect, a method includes inserting a barrel of animplantable device into an interspinous space. The implantable medicaldevice includes the barrel having a first portion and a second portion,a first plate having multiple projections extending from one side of thefirst plate and a second plate having multiple projections extendingfrom one side of the second plate. The method includes expanding thebarrel from a collapsed form having a first height to an expanded formhaving a second height, where the second height is greater than thefirst height, moving the first plate on the first portion to engage aspinous process and moving the second plate on the second portion toengage the spinous process.

Implementations may include one or more of the following features. Forexample, the method may include engaging set screws in the first plateand the second plate to lock the first plate and the second plate inposition. The method may include positioning the first plate to adesired angle with respect to the first portion, positioning the secondplate to a desired angle with respect to the second portion and engagingset screws in the first plate and the second plate to lock the firstplate and the second plate in position.

In another general space, an implantable device may include a barrel,the barrel having an upper portion and a lower portion. The implantabledevice may further include an actuator assembly disposed in the barrel,the actuator assembly comprising a front ramped actuator in engagementwith the barrel, a rear ramped actuator in engagement with the barrel,and a central screw that extends from the rear ramped actuator throughthe front ramped actuator. The implantable device may further include afirst plate having multiple projections extending from one side of thefirst plate, the first plate comprising a first portion that extendsfrom the upper portion and a second portion that extends form the lowerportion. The implantable device may further include a second platehaving multiple projections extending from one side of the second plate,the second plate configured to be received on the central screw. Thebarrel may be configured to transition from a collapsed form having afirst height to an expanded form having a second height and wherein thesecond height is greater than the first height.

In another general aspect, a method may include implanting a medicaldevice in a patient, the method comprising: inserting a barrel of thedevice between adjacent spinous process, the medical device comprising afirst plate disposed on one end of the barrel; rotating a central screwdisposed in the barrel to cause the barrel to expand from a collapsedform having a first height to an expanded form having a second height;and ratcheting a second plate onto the central screw such that the firstplate and the second plate engage the adjacent spinous process, thesecond plate being free to rotate about its center within a range ofmotion.

The details of one or more implementations are set forth in theaccompanying drawings and the description below. Other features will beapparent from the description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a medical device according to an exampleimplementation.

FIG. 2 is a top view of the medical device of FIG. 1.

FIG. 3 is a front view of the medical device of FIG. 1.

FIG. 4 is a side view of the medical device of FIG. 1.

FIG. 5 is a perspective view of a medical device according to an exampleimplementation.

FIG. 6 is a top view of the medical device of FIG. 5.

FIG. 7 is a front view of the medical device of FIG. 5.

FIG. 8 is a side view of the medical device of FIG. 5.

FIG. 9 is a perspective view of a medical device according to an exampleimplementation.

FIG. 10 is a top view of the medical device of FIG. 9.

FIG. 11 is a front view of the medical device of FIG. 9.

FIG. 12 is a side view of the medical device of FIG. 9.

FIG. 13 is a perspective view of a medical device according to anexample implementation.

FIG. 14 is a top view of the medical device of FIG. 13.

FIG. 15 is a front view of the medical device of FIG. 13.

FIG. 16 is a side view of the medical device of FIG. 13.

FIG. 17 is a perspective view of a medical device according to anexample implementation.

FIG. 18 is a top view of the medical device of FIG. 17.

FIG. 19 is a front view of the medical device of FIG. 17.

FIG. 20 is a side view of the medical device of FIG. 17.

FIG. 21 is a top view of a medical device according to an exampleimplementation.

FIG. 22 is a side view of the medical device of FIG. 21.

FIG. 23 is a detailed view of the inset A of FIG. 22.

FIGS. 24-27 are side views of a plate of a medical device according toan example implementation.

FIG. 28 is top view of a barrel of a medical device according to anexample implementation.

FIG. 29 is an exploded front view of a barrel of a medical deviceaccording to an example implementation.

FIG. 30 is an exploded top view of a barrel of a medical deviceaccording to an example implementation.

FIG. 31 is a perspective view of a medical device according to anexample implementation.

FIG. 32 is a top view of the medical device of FIG. 31.

FIG. 33 is a front view of the medical device of FIG. 31.

FIG. 34 is a side view of the medical device of FIG. 31.

FIG. 35 is a perspective view of a medical device according to anexample implementation.

FIG. 36 is a top view of the medical device of FIG. 35.

FIG. 37 is a front view of the medical device of FIG. 35.

FIG. 38 is a side view of the medical device of FIG. 35.

FIG. 39 is a perspective view of a medical device according to anexample implementation.

FIG. 40 is a top view of the medical device of FIG. 39.

FIG. 41 is a front view of the medical device of FIG. 39.

FIG. 42 is a side view of the medical device of FIG. 39.

FIG. 43 is a perspective view of a medical device according to anexample implementation.

FIG. 44 is a top view of the medical device of FIG. 43.

FIG. 45 is a front view of the medical device of FIG. 43.

FIG. 46 is a side view of the medical device of FIG. 43.

FIG. 47 is an exploded top view of a barrel of a medical deviceaccording to an example implementation.

FIG. 48 is a flow chart illustrating an exemplary method including themedical device of FIG. 1.

FIG. 49 is a perspective view of a medical device according to oneimplementation.

FIG. 50 is an exploded view of the medical device of FIG. 49 with thelocking plate removed according to one implementation.

FIG. 51 is a side view of the medical device of FIG. 50.

FIG. 52 is a front view of the medical device of FIG. 50.

FIG. 53 is a rear view of the medical device of FIG. 50.

FIG. 54 is a top view of the medical device of FIG. 50.

FIG. 55 is a side view of the medical device of FIG. 49 with the lockingplate removed according to one example implementation.

FIG. 56 is a front view of the medical device of FIG. 55.

FIG. 57 is a rear view of the medical device of FIG. 55.

FIG. 58 is a top view of the medical device of FIG. 55.

FIGS. 59-62 illustrate assembly of an expandable central barrel of amedical device according to one example implementation.

FIGS. 63-65 illustrate assembly of the spikes for the medical device ofFIGS. 59-62.

FIG. 66 is a side view of a locking plate for a medical device accordingto one example implementation.

FIG. 67 is a front view of the locking plate of FIG. 66.

FIG. 68 is a cross-sectional view of a trunion assembly for a medicaldevice according to one example implementation.

FIG. 69 is a front view of the trunion assembly of FIG. 68.

FIG. 70 is cross-sectional view of a tube that can be used to releasethe pawls of the trunion assembly of FIG. 68 according to one exampleimplementation.

FIGS. 71-73 illustrate assembly of a locking plate for a medical deviceaccording to one example implementation.

FIG. 74 is a side view showing rotation of a locking plate for a medicaldevice according to one example implantation.

FIG. 75 is a perspective view showing angulation of the spike assemblyof the locking plate of FIG. 74.

DETAILED DESCRIPTION

Detailed implementations of the present invention are disclosed herein;however, it is to be understood that the disclosed implementations aremerely examples of the invention, which may be embodied in variousforms. Therefore, specific structural and functional details disclosedherein are not to be interpreted as limiting, but merely as a basis forthe claims and as a representative basis for teaching one skilled in theart to variously employ the present invention in virtually anyappropriately detailed structure. Further, the terms and phrases usedherein are not intended to be limiting, but rather to provide anunderstandable description of the invention.

The terms “a” or “an,” as used herein, are defined as one or more thanone. The term “another,” as used herein, is defined as at least a secondor more. The terms “including” and/or “having”, as used herein, aredefined as comprising (i.e., open transition).

The devices and methods described herein are generally directed tomedical devices that can be used to support, stabilize and/or replaceanatomical structures within a body of a patient. In someimplementations, the devices and methods described herein are configuredto provide support to a spine or back of a patient, including providingsupport between two vertebrae in the spine or back of the patient. Inother implementations, other portions of the body of the patient can besupported by the devices described herein.

The medical devices described herein may be implanted within a body of apatient to assist in maintaining normal physiologic motion in the spineof the patient.

The term patient may be used hereafter for a person who benefits fromthe medical device or the methods disclosed in the present invention.For example, the patient may be a person whose body receives the medicaldevice disclosed by the present invention in a surgical treatment. Forexample, in some embodiments, the patient may be a human female, humanmale, or any other mammal.

This document describes implementations of an implantable medical devicethat may be used as a posterior, non-pedicle supplemental fixationdevice for use in the non-cervical spine. The medical device may be usedas an interspinous fusion device. The medical device may be implantedwith or without the removal of the supraspinous ligament. In one or moreimplementations, the supraspinous ligament may be preserved. The medicaldevice may be attached firmly to the spinous processes above and belowan interspinous space. The medical device may immobilize a lumbar motionsegment posteriorly with no other devices implanted. The medical devicemay withstand compressive, torsional and shear loads seen in the lumbarspine. The medical device may be used to achieve supplemental fusion andto treat conditions of the spine such as, for example, degenerative discdisease, spondylolisthesis, trauma (i.e., fracture or dislocation),tumor and/or other conditions.

This document describes implementations of an implantable medicaldevice, where the medical device may include an expandable centralbarrel with polyetheretheketone (PEEK) bone contacting endplates, withtwo spiked plates attached to the central barrel. For example, the twospiked plate may be held together on posterior rails. By way of furtherexample, one of the spiked plates may be on one end of the expandablecentral barrel (e.g., integrally formed with the central barrel) withanother one of the spiked plates being attached after the barrel isinserted into the interspinous space to clamp the device in place. Theplates may include projections (e.g., spikes) that bite into the spinousprocess to clamp the device in place. Each of the plates may angulate toconform to the patient anatomy. The plates may be locked with a setscrew and may have a lordotic profile to match the lumbar anatomy. Theexpandable barrel may provide interspinous distraction, off-loading thespikes on the plate and reducing the chances of breaking the spinousprocess. The barrel may be sized to fit into the interspinous spacewithout resistance, and then expanded. The barrel may include a graftwindow (e.g., anteriorly and posteriorly) which may be packed with graftmaterial after expansion. In some embodiments, the barrel includes agraft window anteriorly and posteriorly and can be packed with the graftmaterial using the posterior window. The PEEK endplates may includeanatomically-shaped grooves for optimal bone contact and fit.

FIGS. 1-4 illustrate a medical device 10 according to one exampleimplementation. The medical device 10 may be implanted in a patient andreferred to as a spinous process fusion device. FIG. 1 is a perspectiveview of the medical device 10 with a barrel illustrated in a collapsedor contracted position and the plates in a separated position relativeto one another. FIGS. 2-4 illustrate a top view, front view and sideview, respectively, of the medical device 10 of FIG. 1, whichillustrates the barrel in the collapsed or contracted position.

The medical device 10 includes a first plate 12, a second plate 14 andan expandable central barrel (also referred to as a barrel) 16. Thebarrel 16 is illustrated in a collapsed state. The barrel 16 includes afirst portion 18 (e.g., a first rail 18) and a second portion 20 (e.g.,a second rail 20). The first rail 18 and the second rail 20 also may bereferred to as the rails 18 and 20. The first rail 18 and the secondrail 20 may be integrally formed with the barrel 16. The first rail 18and the second rail 20 also may be referred to as posterior rails. Thefirst plate 12 and the second plate 14 (also referred to as the plates12 and 14) may be secured to the barrel 16 by coupling the first plate12 to the first rail 18 and the second plate 14 to the second rail 20.The first plate 12 and the second plate 14 each may include a bushing 22(e.g., a spherical bushing) assembled into the plates 12 and 14, wherethe plates 12 and 14 slide on the respective rails 18 and 20 through thebushing 22 and are secured using a set screw 24. As discussed in moredetail below, each plate 12 and 14 may move laterally along itsrespective rail 18 and 20 to engage spinous processes of adjacentvertebra above and below the interspinous space. FIGS. 1-4 illustratethe plates 12 and 14 in a separated position with respect to oneanother. Also, as discussed in more detail below, each plate 12 and 14may angulate through a range of degrees with respect to the rails 18 and20 to better conform to patient anatomy when implanted in a patient.

In other example implementations (not shown), the first portion 18 andthe second portion 20 may be grooves on the barrel 16. In this example,the first plate 12 and the second plate 14 each may include a projection(e.g., a rail) that is movably inserted into the corresponding groove onthe barrel 16. This example implementation may function in the same wayas described above and below, other than the structure of the rails maybe implemented on the plates 12 and 14, which are then received in thefirst portion 18 and the second portion 20 of the barrel 16, where thefirst portion 18 and the second portion 20 are grooves on the barrel 16.

The first plate 12 may include an upper portion 26 and a lower portion28. The second plate 14 may include an upper portion 30 and a lowerportion 32. The plates 12 and 14 may include multiple projections 34(e.g., spikes) on both the upper portions 26 and 30 and the lowerportions 28 and 32. While the term spikes may be used for theprojections 34 other types of projections may be used that may have amore tapered point or rounded point or other type of ending to theprojection. The spikes 34 may be used to attach firmly and bite into thespinous processes above and below an interspinous space. The spikes 34may be integrally formed with the plates 12 and 14 or the spikes 34 maybe separate components that are secured to the plates 12 and 14. Thespikes 34 may be pyramid shaped with a base portion secured orintegrally formed on the plates 12 and 14. The sides of the spikes 34may extend from the base to form a point in the shape of a pyramid. Inother example implementations, the spikes 34 may be formed into othershapes that rise to a point to enable the spike to engage the spinousprocess. As discussed above, the end of the spikes 34 may include tipsother than a point such as, for example, rounded tip, a square tip orother-shaped tip.

The plates 12 and 14 and the spikes 34 may be made of titanium. In otherimplementations, the plates 12 and 14 and the spikes 34 may be made ofother biocompatible materials.

The example illustration of the medical device 10 includes four (4)spikes 34 on each portion 26, 28, 30 and 32 of the plates 12 and 14. Inother example implementations, fewer or more spikes 34 may be included.In one example implementation, the spikes 34 on opposing portions (i.e.,upper portions 26 and 30 and lower portions 28 and 32) may be alignedacross from one another. In other example implementations, the spikes 34on opposing portions may be offset from one another.

The first plate 12 and the second plate 14 may be shaped in a lordoticprofile to match the lumbar anatomy. With respect to the first plate 12,the upper portion 26 is connected to the lower portion 28 by a centralportion 36. The upper portion 26, the lower portion 28 and the centralportion 36 may be integrally formed as a single plate component. Thecentral portion 36 includes an open side (e.g., a C-shaped opening) toreceive the bushing 22 and an opening (e.g., a hole) to receive the setscrew 24, as illustrated in more detail in FIGS. 24-27. In other exampleimplementations, the first plate 12 and the second plate 14 may be othershapes suitable for a particular application.

Similarly to the first plate 12, the second plate 14 includes a centralportion 38 that connects the upper portion 30 to the lower portion 32.The upper portion 30, the lower portion 32 and the central portion 38may be integrally formed as a single plate component. The centralportion 38 include an open side (e.g., a C-shaped opening) to receivethe bushing 22 and an opening (e.g., a hole) to receive the set screw24, as illustrated in more detail in FIGS. 24-27. The set screw 24 isused to lock the plates 12 and 14 in an angular position at any positionwithin their range of angular motion.

The central barrel 16 is an expandable barrel that may be in a collapsedposition for insertion into a patient in the interspinous space withoutresistance and then expanded up to the barrel's maximum height. In oneexample implementation, the maximum expanded height of the barrel may beabout 4 mm greater than the collapsed height.

The central barrel 16 includes a first endplate 40 and a second endplate42 (also referred to as endplates 40 and 42), as best viewed in FIG. 3.Each of the endplates 40 and 42 includes a respective groove 44 and 46.The grooves 44 and 46 may be anatomically-shaped grooves optimal bonecontact and fit in the patient. The endplates 40 and 42 may be PEEK bonecontacting endplates. The barrel 16 may be bullet-shaped on both ends inthe lateral and posterior directions to facilitate insertion into apatient. The expandable barrel 16 may provide interspinous distractionand may offload the forces of the spikes 34 on the plates 12 and 14 toreduce the chances of breaking a spinous process. The barrel 16 may beinserted, laterally or posteriorly, in a smaller height and thenexpanded to provide distraction, eliminating forces on the spinousprocess and potential frustration for a surgeon performing theimplantation.

The barrel 16 includes a first window 48 (e.g., also referred to as anopening or an anterior window) and a second window 50 (e.g., alsoreferred to as an opening or a posterior window). The first window 48and the second window 50 may be used as graft windows for the packing ofbone graft material following the insertion and placement of the medicaldevice 10 in a patient. In one implementation, after the barrel 16 hasbeen expanded, the barrel 16 may be packed with bone graft using thesecond window 50. In this manner, graft containment areas accessed bythe windows 48 and 50 may provide for a larger grafting area and may bepacked after expansion of the barrel 16.

Referring to FIGS. 5-8, an example implementation of the medical device10 of FIGS. 1-4 is illustrated with the barrel 16 shown in an expandedstate and the plates 12 and 14 shown in a separated position withrespect to one another. That is, the plates 12 and 14 are eachpositioned towards an outer end of the rails 18 and 20. The barrel 16expands and contracts by expanding and contracting the endplates 40 and42 in a direction towards the upper 26 and 30 and lower portions 28 and32 of the sides 12 and 14, respectively. The mechanism to expand andcontract the barrel 16 is illustrated in more detail in FIGS. 28-30below.

In general, a central screw 52 is rotated to actuate two independentinternal actuators. The actuators include split ramps that raise andlower the endplates 40 and 42 when the central screw 52 is rotated.FIGS. 7 and 8 provide views that illustrate the barrel 16 in a fullyexpanded state. As discussed above, the barrel 16 may be expanded afterinsertion into the interspinous space. After expansion, the barrel 16may be packed with bone graft material using the window 50. Prior toexpansion, some bone graft material may be packed into the barrel 16using the window 48.

Referring to FIGS. 9-12, an example implementation of the medical device10 of FIGS. 1-4 is illustrated with the barrel 16 shown in a collapsedstate and the plates 12 and 14 shown in a closed position. That is, theplates 12 and 14 have been traversed along the rails 18 and 20 towardsone another. The plates 12 and 14 may slide along the rails 18 and 20and may be secured in position at any point along the rails 18 and 20using the set screw 24. When the plates 12 and 14 are slid togetheralong the rails 18 and 20, the spikes 34 on the plates 12 and 14 mayengage and clamp (or bite into) the spinous process. In this manner, thespikes 34 on the upper portions 26 and 30 may clamp together and intoone spinous process and the spikes 34 on the lower portions 28 and 32may clamp together and into an adjacent spinout process.

As illustrated in FIGS. 9-12, the spikes 34 on one plate are aligned tomate at a same point with the spikes 34 on an opposing plate. In otherexample implementations, the spikes 34 on one plate may be offset inrelation to the spikes 34 on an opposing plate.

Referring to FIGS. 13-16, an example implementation of the medicaldevice 10 of FIGS. 1-4 is illustrated with the barrel 16 shown in anexpanded state and the plates 12 and 14 shown in a closed position. Inthis manner, this illustrates the medical device 10 in a state afterinsertion into the patient such that the plates 12 and 14 have beentraversed along the rails 18 and 20 to clamp on the spinous process ofadjacent vertebrae and the barrel 16 has been expanded using the centralscrew 52.

Referring to FIGS. 17-23, an example implementation of the medicaldevice 10 of FIGS. 1-4 is illustrated with the barrel 16 shown in anexpanded state and the plates 12 and 14 shown in an open or separatedposition and in an angulated configuration. As discussed above, theplates 12 and 14 may rotate angularly with respect to the rails 18 and20. The plates 12 and 14 may pivot around the bushing 22 and may belocked in place using the set screw 24. In one example implementation,the plates 12 and 14 may have a range of motion of about 25 degreesoffset with respect to the rails 18 and 20. The angulation of the plates12 and 14 enables each plate to conform independently to the anatomy ofthe particular patient. Each plate 12 and 14 may be pivoted and lockedat any position in their range of motion independent of the other plate.

In FIGS. 22 and 23, a side view (FIG. 22) and a detailed view of inset A(FIG. 23) illustrate that the plates 12 and 14 are locked using the setscrew 24. The rails 18 and 20 may be C-shaped or curved and include agroove area 60. The set screw 24 may include a curved, cup-shaped designon the tip 62. The curved tip 62 penetrates through the opening in therail 14 and through the bushing 22 to engage the groove area 62 of therail 20 to secure and lock the plate 14 in place. The curved tip 62maximizes the surface contact with the groove area 62 of the rail 20when the plate 14 pivots through its range of motion. FIGS. 24-27 belowalso illustrate the curved (or cup-shaped or bulleted) tip 62 of the setscrew 24.

Referring to FIGS. 24-27, the assembly of the plates 12 and 14 isillustrated. In these example figures, plate 14 is referenced forillustrative purposes. The plate 14 may be assembled by placing thebushing 22 into the plate initially offset by 90 degrees from its finalposition. As described above, the bushing 22 may be a spherical bushingthat is shaped to be positioned on and traverse the rail 20 on thebarrel 16. The bushing 22 may include a slot 64 or opening in the backof the bushing to receive the set screw 24.

Once the bushing 22 has been inserted into the plate 14 (FIG. 25), thebushing 22 is rotated 90 degrees into its final position in the plate 14(FIG. 26). Then, the set screw 24 having the curved tip 62 may beinserted through the opening in the back of the plate 14 through theslot 64 in the bushing 22. The set screw 24 serves to prevent thebushing 22 from rotating back out of the plate 14.

Referring to FIGS. 28-30, the barrel 16 and assembly of the barrel 16 isillustrated in detail. As discussed above, the barrel 16 includes afirst endplate 40 and a second endplate 42. The endplates 40 and 42 maybe PEEK endplates. The barrel 16 includes a central screw 52 having afirst thread portion 66 and a second thread portion 68. The barrel 16includes a frame 65, a first actuator 70 and a second actuator 72 (alsoreferred to as the actuators 70 and 72) and two assembly pins (notshown). In one example implementation, the frame 65, the actuators 70and 72 and the central screw 52 may be made of titanium. In otherexample implementations, the components may be made of otherbiocompatible materials.

Each of the actuators 70 and 72 may include split ramps 74 and 76 toaccommodate the curved shape of the barrel 16. The barrel 16 is curvedshaped and may be bulleted (or egg-shaped) on each end to allow foreasier insertion into the interspinous space. The curved shape of thebarrel 16 may provide maximum graft packing volume.

The actuators 70 and 72 may be loosely assembled into the frame 65 ofthe barrel 16 and the 74 and 76 placed over the actuators 70 and 72. Thecentral screw 52 may be inserted into the actuators 70 and 72 and timedso that the actuators have specific spacing per rotation of the screw52. Once the screw 52 is fully inserted, two pins (not shown) arepressed into the frame 65 posteriorly to capture the screw 52 to preventits disassembly.

The rotation of the screw 52 causes the actuators 70 and 72 to rotateand the ramps 74 and 76 on the actuators 70 and 72 to push against theendplates 40 and 42, causing the endplates 40 and 42 to expand from acollapsed position. A counter rotation of the screw 52 causes theactuators 70 and 72 to rotate and the ramps 74 and 76 on the actuators70 and 72 to recede from pushing against the endplates 40 and 42,causing the endplates 40 and 42 to collapses from an expanded state.

FIGS. 31-34 illustrate a medical device 100 according to an exampleimplementation. Similarly to the medical device 10, the medical device100 may be implanted in a patient and referred to as a spinous processfusion device. Like reference numbers between the FIGS. 1-30 and FIGS.31-34, and other figures below describing medical device 100, refer tothe same or similar components and features between the two medicaldevices. The medical device 100 may have the same features andfunctionality as the medical device 10.

The medical device 100 includes a first plate 12 and a second plate 14.The medical device 100 includes a barrel 116. In the example of FIGS.31-34, the barrel 116 includes rails 118 and 120 that each extend from adifferent side of the barrel 116 instead of extending from a same sidelike the rails 18 and 20 from the barrel 16 in medical device 10. Thebarrel 116 is essentially rotated 90 degrees compared to the barrel 16.In other aspects, the barrel 116 is an expandable barrel and has thesame functionality as the barrel 16. The barrel 116 may be insertedlaterally into a patient in the interspinous space. The barrel 116 maybe inserted at a smaller height (or in a collapsed state) and thenexpanded to provide distraction and to eliminate the forces on thespinous process and frustration for the surgeon.

In FIGS. 31-34, the medical device 100 illustrates the plates 12 and 14in an open state and the barrel 116 in a collapsed state. In thismanner, the medical device 100 may inserted into a patient and then thebarrel 116 expanded.

Referring to FIGS. 35-38, the medical device 100 is illustrated with thebarrel 116 in an expanded state. In one example implementation, theexpanded barrel height for the barrel 116 may be about 7 mm greater thanthe collapsed height. The sides 12 and 14 are illustrated in an openstate. The barrel 116 may be expanded from a collapsed state to anexpanded state using the central screw 152. Similarly, the barrel 116may be collapsed from an expanded state to a collapsed state using thecentral screw 152.

Referring to FIGS. 39-42, the medical device 100 is illustrated with thebarrel 116 in an expanded state and the plates 12 and 14 in a closedposition. As discussed above with respect to the medical device 10, theplates 12 and 14 on the medical device 100 also may traverse the rails118 and 120 of the barrel between an open position and a closedposition. In the closed position, the plates 12 and 14 are designed toclamp and bite into the spinous process, as discussed above in detail.

Referring to FIGS. 43-46, the medical device 100 is illustrated with thebarrel 116 in an expanded state and the plates 12 and 14 in a closed andangulated position. As discussed above with respect to FIGS. 17-20, theplates 12 and 14 may angulate about 25 degrees with respect to the rails118 and 120 to better conform to patient anatomy. The plates 12 and 14may be locked in position using the set screw 24.

Referring to FIG. 47, the barrel 116 is assembled in a manner similar tothe barrel 16, as discussed above with respect to FIGS. 28-30. Thebarrel 116 includes a first endplate 140 and a second endplate 142, twoindependent actuators with ramps and a central screw 152. The endplates140 and 142 are loosely assembled into the actuator ramps and thecentral screw 152 is inserted into the actuator ramps, which anchor theassembly together.

Referring to FIG. 48, an example flowchart illustrates an exampleprocess 200 for using the medical devices 10 and 100. For example,process 200 includes inserting a barrel 16 or 116 of the medical device10 or 100, respectively, into an interspinous space (210). As discussedabove, the medical device includes the barrel 16 or 116 having a firstportion (e.g., rail 18 or 118) and a second portion (e.g., rail 20 or120), a first plate 12 having multiple projections 34 extending from oneside of the first plate 12 and a second plate 14 having multipleprojections 34 extending from one side of the second plate (210).

The process 200 includes expanding the barrel 16 or 116 from a collapsedform having a first height to an expanded form having a second height,where the second height is greater than the first height (220). Asdiscussed above, the central screw 52 or 152 may be rotated to expandthe barrel 16 or 116 from a collapsed form to an expanded form in theinterspinous space.

The process includes moving the first plate 12 on the first portion(e.g., rail 18 or 118) to engage a spinous process (230) and moving thesecond plate 14 on the second portion (e.g., rail 20 or 120) to engagethe spinous process (240). For example, the projections 34 on each ofthe plates 12 and 14 may engage the spinous process of adjacentvertebrae as the plates 12 and 14 are slid along the respective rails.

Optionally, the process 200 may include positioning the first plate 12to a desired angle with respect to the first portion and positioning thesecond plate 14 to a desired angle with respect to the second portion.Once the plates 12 and 14 have been positioned to their desired angles,the plates 12 and 14 may be locked into position using the set screws24.

FIG. 49 illustrates a medical device 300 according to one exampleimplementation. FIG. 49 is a perspective view of the medical device 300.The medical device 300 may be implanted into a patient and referred toas a spinous process fusion device. In the illustrated embodiment, themedical device 300 includes a first plate 302, a second plate 304 (e.g.,locking plate 304), and an expandable central barrel (also referred toas a barrel) 306.

With additional reference to FIGS. 50-54, the medical device 300 of FIG.49 will be described in more detail. FIGS. 50-54 illustrate an explodedview, side view, front view, rear view, and top view, respectively, ofthe medical device 300, which illustrate the barrel 306 in the collapsedor contracted position with the locking plate 304 removed. The barrel306 may be inserted into the interspinous space without the lockingplate 304 and then expanded. The locking plate 304 may then be attachedto the barrel 306 after insertion to the lock the medical device 300 inplace in engagement with the spinous process.

Win the illustrated embodiment, the barrel 306 includes a first portion308 (e.g., upper portion 308) and a second portion 310 (e.g., lowerportion 310). The first portion 308 may include a pair of ramped uppersidewalls 312. The ramped upper sidewalls 312 may include rampedportions 316 on either end of the ramped sidewalls 314. The secondportion 312 may also include a pair of ramped lower sidewalls 314. Theramped lower sidewalls 314 may include ramped portions 318 on eitherend. As best seen in FIG. 51, the ramped lower sidewalls 314 and theramped upper sidewalls 312 may overlap when the medical device 10 iscollapsed. The ramped upper sidewalls 312 and the ramped lower sidewalls314 may define a central chamber in the barrel 306. The central chamber315 may be used for the packing of bone graft material following theinsertion and placement of the medical device 10 in a patient. In oneimplementation, after the barrel 306 has been expanded, the barrel 306may be packed with bone graft using the central chamber 315. In thismanner, the central chamber 315 may provide for a larger grafting areaand may be packed after expansion of the barrel 306.

The central barrel 306 is an expandable barrel that may be in acollapsed position for insertion into a patient in the interspinousspace without resistance and then expanded up to the barrel's maximumheight. In one example implementation, the maximum expanded height ofthe barrel may be about 4 mm greater than the collapsed height or,alternatively, about 6 mm greater than the collapsed height. The centralbarrel 306 may provide interspinous distraction and may offload theforces of the spikes 328, 362 on the plates 302 and 304 to reduce thechances of breaking a spinous process. The barrel 306 may be inserted,laterally or posteriorly, in a smaller height and then expanded toprovide distraction, eliminating forces on the spinous process andpotential frustration for a surgeon performing the implantation.

The first plate 302 may include an upper portion 320 and a lower portion322. The upper portion 320 of the first plate 302 may extend generallyvertically from the first portion 308 of the barrel 306. The upperportion 320 may be integrally formed with the first portion 308. Thelower portion 322 of the first plate 302 may extend from the secondportion 310 of the barrel 306 in a direction generally opposite to theupper portion 320. The lower portion 322 may be integrally formed withthe second portion 310. The first plate 302 may be shaped in a lordoticprofile to match the lumbar anatomy.

The first plate 302 may include a spike assembly 324 on both the upperportion 320 and the lower portion 322. The spike assemblies 324 may eachbe received within an opening 326 in both the upper portion 320 and thelower portion 322. Each spike assembly 324 may include multipleprojections (e.g., spikes 328) that extend from a spike sphere 330. Thespike spheres 330 may each be a complete sphere, hemisphere, or aspheric section. Each spike assembly 324 may further comprise a wedge332 and a post 334. The wedge 332 may be secured onto the post 334 withthe spike sphere 330 fit onto the wedge 332 over the post 334. A pin(not shown) may be used in the opening 326 to prevent rotation of thespike sphere 330 in the opening 326 while allowing articulation of thespike sphere 330 with respect to the first plate 302. Slots 336 may bedisposed in the spike sphere 330, as best seen on FIG. 49.

While the term “spikes” may be used for the projections other types ofprojections may be used that may have a more tapered point or roundedpoint or other type of ending to the projection. The spikes 328 may beused to attach firmly and bite into the spinous processes above andbelow an interspinous space. While spike assemblies 324 are shown, otherembodiments may include spikes 328 that are integrally formed with thefirst plate 302. The spikes 328 may be pyramid shaped with a baseportion secured or integrally formed on the spike sphere 330. The sidesof the spikes 328 may extend from the base to form a point in the shapeof a pyramid. In other example implementations, the spikes 328 may beformed into other shapes that rise to a point to enable the spike toengage the spinous process. As discussed above, the end of the spikes328 may include tips other than a point such as, for example, roundedtip, a square tip or other-shaped tip. The example illustration of themedical device 10 includes three (3) spikes 328 on each spike assembly324 of the first plate 302. In other example implementations, fewer ormore spikes 328 may be included. The first plate 302 and the spikes 328may be made of titanium. In other implementations, the first plate 302and the spikes 328 may be made of other biocompatible materials.

The medical device 10 may further include an actuator assembly 338 (bestseen on FIG. 50) for raising and lowering the first and second portions308 and 310 of the barrel 306 and, thus, the upper and lower portions320, 322 of the first plate 302. The actuator assembly 338 may bedisposed between the first and second portions 308 and 310 of the barrel306. As illustrated, the actuator assembly 338 may comprise a centralscrew 340, a front ramped actuator 342 and a rear ramped actuator 344.The front ramped actuator 342 may be bullet shaped on its front end tofacilitate insertion into a patient. The front ramped actuator 342 mayhave a ramped expansion portion 346 and an extension portion 348. Theramped expansion portion 346 may be located at a front end of the barrel306 with the extension portion 348 extending from the ramped expansionportion 346 towards a rear end of the barrel 306. The central screw 340may extend through the barrel 306 and engage the extension portion 348.The first and second portions 308 and 310 of the barrel 306 mayslidingly engage the ramped expansion portion 346. For example, theramped expansion portion 346 may engage ramped surface 316 of the firstand second portions 308 and 310 at a front end of the barrel 306. Theramped expansion portion 346 may have dovetail connections with thefirst and second portions 308 and 310, respectively. The rear rampedactuator 344 may be disposed at a rear end of the barrel 306. The firstand second portions 308 and 310 of the barrel 306 may slidingly engagethe rear ramped actuator 344. For example, the rear ramped actuator 344may also engage ramped surfaces 316 of the first and second portions 308and 310 of the barrel. The rear ramped actuator 344 may have dovetailconnections with the first and second portions 308 and 310,respectively. The central screw 340 may extend through the rear rampedactuator 344 to engage the extension portion 348.

Referring to FIGS. 56-58, an example implementation of the medicaldevice of FIGS. 49-55 is illustrated with the barrel 306 shown in anexpanded state. The barrel 306 expands by forcing the first and secondportions 308 and 310 vertically outward in a direction away from oneanother. In this manner, the upper and lower portions 320 and 322 of thefirst plate 302 are also expanded vertically outward. The barrel 306contracts by forcing the first and second portions 308 and 310 tocontract in a direction toward one another, thus also moving the upperand lower portions 320 and 322 of the first plate 302 together. In someembodiments, the actuator assembly 338 may be used to raise and lowerthe first and second portions 308 and 310. By way of example, thecentral screw 340 may be turned to contract the actuator assembly 338.The rear ramped actuator 342 may be held in place while the centralscrew 340 is turned causing the front ramped actuator 340 to be drawntoward the rear ramped actuator 342. The rear ramped actuator 342 andthe front ramped actuator 340 may engage the ramped upper sidewalls 312and the ramped lower sidewalls 314 in the first and second portions 308and 310 forcing the first and second portions 308 and 310 to expand froma collapsed position. A counter rotation of the central screw 340 maycause the front ramped actuator 340 and the rear ramped actuator 342 toseparate causing the first and second portions 308 and 310 to collapsefrom the expanded state.

Referring to FIGS. 59-62, assembly of the barrel 306 of the medicaldevice 300 shown on FIGS. 49-58 will now be described according to anexample implementation. As illustrated by FIG. 59, the barrel 306 maycomprise a first portion 308 and a second portion 310. The first plate302 may be defined by upper portion 320 and lower portion 322. Upperportion 320 may extend from first portion 308 of the barrel 306, andlower portion 322 may extend in an opposite direction from secondportion 310 of the barrel 306. As further illustrated by FIG. 59, theactuator assembly 338 may comprise a central screw 340, a front rampedactuator 342, and a rear ramped actuator 344. In FIG. 60, the rearramped actuator 344 may be slid onto the first portion 308 of the barrel306. As illustrated, the rear ramped actuator 344 may be engage (e.g.,through a dovetail connection) a rear end of the upper ramped sidewalls312 of the first portion 308. In FIG. 61, the front ramped actuator 342may then the slide onto the second portion 310 of the barrel 306. Asillustrated, the ramped expansion portion 346 may engage (e.g., througha dovetail connection) a front end of the lower ramped sidewalls 314 ofthe second portion 310. In FIG. 62, the first portion 308 and secondportion 310 of the barrel 306 have been placed together in a contractedposition with a front end of the upper ramped sidewalls 312 engaging theramped expansion portion 346 and a rear end of the lower rampedsidewalls 314 engaging the rear ramped actuator 344.

Referring to FIGS. 63-65, assembly of the spike assemblies 324 of themedical device 300 shown on FIGS. 49-58 will now be described accordingto an example implementation. As illustrated by FIG. 63, the spikeassemblies 324 each comprise a spike sphere 330, a wedge 332, and a post334. In FIG. 64, the post 334 may be inserted into the wedge 332coupling the post 334 and the wedge 332. The wedge 332 may be securedonto one end of the post 334. Each assembly of the post 334 and wedge332 may then be placed into the opening 326 in the upper and lowerportions 320 and 322 of the first plate 302. The spike sphere 330 maythen be placed onto the other end of the post 334, which may be thenpressed back into the open 326, as seen in FIG. 65. In one embodiment, asnap connection may secure the spike sphere 330 the post 334. A pin (notshown) may be used in the opening 326 to prevent rotation of the spikesphere 330 assembly 324 in the opening 326 while allowing articulationof the spike sphere 330 with respect to the first plate 302. In someembodiments, slots 336 in the spike sphere 330 allow the spike sphere330 to expand and collapse. To lock the spike sphere 330 in a particularorientation, the wedge 332 may be compressed further into the opening326 causing the spike sphere 330 to expand outward and lock.

Referring to FIGS. 49 and 66-67, the second or locking plate 304 willnow be described in more detail with respect to one exampleimplementation. FIG. 49 is a perspective view of the medical device 10with the locking plate 304. FIGS. 66 and 67 are side and front views,respectively, of the locking plate 304. The locking plate 304 may beinserted onto the central screw 340 after the barrel 306 has beenexpanded to lock the barrel 306 in position.

As illustrated, the locking plate 304 may comprise an upper portion 350and a lower portion 352. A central portion 354 may connection the upperportion 350 to the lower portion 352. The upper portion 350, lowerportion 352, and central portion 354 may be integrally formed as asingle plate component. The central portion 354 includes an opening(e.g., a central opening) to receive trunion assembly 356 (best seen onFIG. 67). The locking plate 304 may rotate about the trunion assembly356 and can be locked at various angles at any position within its rangeof motion. In some embodiments, the trunion assembly 356 may beconfigured so that the locking plate 304 rotates about its center. Thelocking plate 304 may include a spike assembly 358 on both the upperportion 350 and the lower portion 352. The spike assemblies 358 may eachbe received within an opening in both the upper portion 350 and thelower portion 352 of the locking plate 304. Each spike assembly 358 maycomprise a spike sphere 360 having multiple projections, such as spikes362. Each spike assembly 358 may further comprise a wedge 364 and a post366. The spike assemblies 358 and its various components may be similarin function and assembly to the spike assembly 324 of the first plate302 discussed above with respect to FIGS. 49-58 and 63-65.

With additional reference to FIGS. 68 and 69, the trunion assembly 356will described in more detail with respect to one exampleimplementation. As illustrated, the trunion assembly 356 may comprise ahousing 368. The housing 368 may have laterally extending projections370 for rotatably coupling the trunion assembly 368 to the centralportion 354 of the locking plate 304 while allowing the locking plate304 to rotate with respect to the trunion assembly 368. As illustrated,there may be a pair of projections 370 that extend from opposite sidesof the housing 368 and are each received in corresponding openings 372in the central portion 354. The housing 368 may further have a throughbore 374 for receiving the central screw 340. The housing 368 mayfurther comprise a pair of chambers 376 on either side of the throughbore 374. The housing 368 may further include a ratchet pawl 378 in eachchamber 376. Embodiments of the ratchet pawls 378 may be spring loadedso that the ratchet pawls 378 may maintain contact with the centralscrew 340 while the locking plate 304 rotates about the trunion assembly368. The ratchet pawls 378 may be assembled from the side of the housing368. The ratchet pawls 378 may each have spring cuts to allow theratchet pawls 378 to compress further into the chambers 376. The springcuts may be the height of an electric discharge machining wire to createa small gap within each leaf of the ratchet pawls 378 beingself-limiting as it collapses upon itself. Insertion of the centralscrew 340 into the through bore 374 (e.g., from right to left of FIG.68) should cause the teeth (or threading) of the central screw 340 toengage the ratchet pawls 378 causing the ratchet pawls 378 to recessinto the chambers 376. The angling of the teeth on the ratchet pawls 378should resist backwards motion of the central screw 340 after insertioninto the through bore 374. In this manner, the ratchet pawls 378 may beoperable to secure the trunion assembly 368 and thus the locking plate304 onto the central screw 340.

FIG. 70 illustrates a tube 380 that can be used to release the ratchetpawls 378 in accordance one example implantation. The tube 380 may besized to fit over the central screw 340. The tube 380 may be advancedover the central screw 340 and into the back end of the through bore 374until the leading end or nose 382 of the tube 380 engages the ratchetpawls 378. Pressure from the tube 380 combined with large chamfers onthe ratchet pawls should cause the ratchet pawls 378 to compress. Whenfully inserted, the tube 380 includes one or more teeth 384 configuredto snap into the ratchet pawls 378 allowing complete release of thecentral screw 340.

As illustrated by FIGS. 68 and 69, the housing 368 may have an uppersurface 386 and a lower surface 388. In embodiments, the upper and lowersurfaces 386 and 388 may each be curved. As illustrated, the upper andlower surfaces 386 and 388 may be sloped inward from the rear to thefront of the housing 368. In some embodiments, the upper and lowersurfaces 386 and 388 may each comprise a projection 390. The projection390 may engage the locking plate 304 to limit its rotation about thetrunion assembly 356.

Referring to FIGS. 71-75, assembly of the locking plate 304 shown onFIGS. 66 and 67 will now be described according to an exampleimplementation. As illustrated by FIG. 71, the locking plate 304 maycomprise an upper portion 350, a lower portion 352, and a centralportion 354 coupling the upper portion 350 and the lower portion 352.The trunion assembly 356 may comprise a housing 368 and a pair ofratchet pawls 378. The housing 368 may comprise a pair of windows 392for receiving the ratchet pawls 378 into chambers 376 (FIG. 68). Theratchet pawls 378 may be inserted into the housing 368 from the side viawindows 392, as shown on FIG. 72. The trunion assembly 356 comprisingthe housing 368 having the ratchet pawls 378 disposed therein may thenbe inserted into the opening in the central portion 354 of the lockingplate 302, as best seen in FIG. 73. The trunion assembly may compriseprojections 370 that are received in openings 372 in the central portion354 to secure the trunion assembly 356 in the central portion 354. Theprojections 370 may be chamfered or otherwise angled on their leadingedges to allow insertion into the openings 372. The plate assemblies 358may then inserted into the upper portion 350 and lower portion 352 ofthe locking plate 304. In embodiments, the spike assemblies 358 may beassembled and inserted into the locking plate 304 in a manner similar tothat discussed above with respect to FIGS. 63-65.

As previously mentioned, the locking plate 304 may be free to rotateabout the trunion assembly 356 even where the trunion assembly 356 is inengagement with central screw 340. FIG. 74 is a side view of the lockingplate 304 illustrating rotation of the locking plate 304 according toone example implementation. Additionally, the spike spheres 360 may alsobe free to articulate with respect to the locking plate 304. FIG. 74illustrates articulation of the spike spheres 360 in accordance to oneexample implantation. Rotation of the locking plate 304 and/orarticulation of the spike spheres 360 can provide an adaptable medicaldevice 10 that can accommodate variances in spinous process geometry,for example, with the goal of anterior and secure placement.

An embodiment for using the medical device 300 will now be described inaccordance with one example implementation. For example, a method maycomprise inserting the barrel 306 of the medical device 300 into aninterspinous space. The method may further comprise expanding the barrel306 from a collapsed form having a first height to an expanded formhaving a second height, where the second height is greater than thefirst height. As discussed above, the central screw 340 may be rotatedto expand the barrel 306 from a collapsed form to an expanded form inthe interspinous space. The process may further include inserting thelocking plate 304 onto the central screw 340 and moving the lockingplate 304 towards the first plate such that the locking plate 304 andthe first plate 302 engage a spinous process. The locking plate 304 maybe free to rotate about its center (e.g., the trunion assembly 356) toaccommodate spinous process geometry. In addition, the spike spheres 324and 360 of the first plate 302 and the locking plate 304, respectively,may also be free to articulate for accommodation of spinous processgeometry. The spike spheres 324 and 360 may be locked into place duringcompression into the spinous process.

The various components of the medical device 10, medical device 100, andmedical device 300 described herein can be formed with any biocompatiblematerial used for such a medical device. For example, each of thevarious components can be formed with one or more biocompatible plasticsand/or one or more biocompatible metals such as, for example, titaniumand stainless steel.

While certain features of the described implementations have beenillustrated as described herein, many modifications, substitutions,changes and equivalents will now occur to those skilled in the art. Itis, therefore, to be understood that the appended claims are intended tocover all such modifications and changes as fall within the scope of theembodiments. It should be understood that they have been presented byway of example only, not limitation, and various changes in form anddetails may be made. Any portion of the apparatus and/or methodsdescribed herein may be combined in any combination, except mutuallyexclusive combinations. The embodiments described herein can includevarious combinations and/or sub-combinations of the functions,components and/or features of the different embodiments described.

What is claimed is:
 1. A method for implanting a medical device in apatient, the method comprising: providing the medical device, the deviceincluding a barrel, a first plate, a second plate, and a central screw;inserting the barrel of the device between adjacent spinous processes,the first plate disposed on one end of the barrel; rotating the centralscrew disposed in the barrel to cause the barrel to expand from acollapsed form having a first height to an expanded form having a secondheight; and ratcheting the second plate onto the central screw such thatthe first plate and the second plate engage the adjacent spinousprocess, the second plate being free to rotate about its center within arange of motion.
 2. The method of claim 1, wherein rotation of thecentral screw draws a front ramped actuator toward a rear rampedactuator, the front ramped actuator and the rear ramped actuator actingon an upper portion and a lower portion of the barrel to cause thebarrel to expand.
 3. The method of claim 2, wherein the upper portion ofthe barrel comprises ramped upper sidewalls in engagement with the rearramped actuator and the front ramped actuator, and wherein the lowerportion of the barrel comprises ramped lower sidewalls in engagementwith the rear ramped actuator and the front ramped actuator.
 4. Themethod of claim 3, wherein the ramped upper sidewalls and the rampedlower sidewalls are overlapping.
 5. The method of claim 3, wherein theramped upper sidewalls and the ramped lower sidewalls define a centralopening configured to receive graft packing material.
 6. The method ofclaim 1, wherein the first portion of the first plate is integrallyformed with the upper portion of the barrel, and wherein the secondportion of the first plate is integrally formed with the lower portionof the barrel.
 7. The method of claim 1, wherein the medical devicefurther includes a plurality of spike assemblies that includeprojections of the first plate and the second plate, wherein the spikeassemblies each comprise: a spike sphere; a post, the spike sphere beingcoupled to the post; and a wedge; wherein the spike sphere of each ofthe spike assemblies is individually disposed in an opening in the firstplate or the second plate, and wherein compression of the spike sphereinto the opening causes the wedge to lock the spike sphere in place. 8.The method of claim 7, wherein the projections of the first plate aredisposed in spike spheres in the first plate, the spike spheres beingconfigured to articulate with respect to the first plate, and whereinthe projections of the second plate are disposed in spike spheres in thesecond plate, the spike spheres being configured to articulate withrespect to the second plate.
 9. The method of claim 1, wherein thesecond height may have a maximum height that is about 6 mm greater thanthe first height.
 10. The method of claim 2, wherein the front rampedactuator may be bullet shaped on its front end.
 11. A method forimplanting a medical device in a patient, the method comprising:inserting a barrel of the device between adjacent spinous processes, themedical device including a first plate disposed on one end of thebarrel; rotating a central screw disposed in the barrel to cause thebarrel to expand from a collapsed form having a first height to anexpanded form having a second height; and ratcheting a second plate ontothe central screw such that the first plate and the second plate engagethe adjacent spinous process, the second plate being free to rotateabout its center within a range of motion, wherein the first plateincludes projections disposed in a first set of spike spheres configuredto be received by the first plate, and wherein the second plate includesprojections disposed in a second set of spike spheres in the secondplate, the second set of spike spheres configured to articulate withrespect to the second plate.
 12. The method of claim 11, whereinrotation of the central screw draws a front ramped actuator toward arear ramped actuator, the front ramped actuator and the rear rampedactuator acting on an upper portion and a lower portion of the barrel tocause the barrel to expand.
 13. The method of claim 12, wherein theupper portion of the barrel comprises ramped upper sidewalls inengagement with the rear ramped actuator and the front ramped actuator,and wherein the lower portion of the barrel comprises ramped lowersidewalls in engagement with the rear ramped actuator and the frontramped actuator.
 14. The method of claim 13, wherein the ramped uppersidewalls and the ramped lower sidewalls are overlapping.
 15. The methodof claim 13, wherein the ramped upper sidewalls and the ramped lowersidewalls define a central opening configured to receive graft packingmaterial.
 16. The method of claim 11, wherein the first portion of thefirst plate is integrally formed with the upper portion of the barrel,and wherein the second portion of the first plate is integrally formedwith the lower portion of the barrel.
 17. The method of claim 11,wherein the second height may have a maximum height that is about 6 mmgreater than the first height.
 18. The method of claim 12, wherein thefront ramped actuator may be bullet shaped on its front end.
 19. Themethod of claim 11, wherein the first set of spike spheres configured toarticulate with respect to the first plate.
 20. The method of claim 19,wherein the second set of spike spheres configured to articulate withrespect to the second plate.